Occasionally it is necessary to shut down a wellhead platform, for example during an emergency or for planned maintenance. When the platform is shut down it is necessary to drain the fluid which has been extracted from a well from the process equipment on the wellhead platform.
The fluid in the process equipment is usually drained using a drainage system on the wellhead platform. A typical drainage system comprises a drainage tank which is connected via drainpipes to all of the low points of the process equipment where the liquid collects. When the system is shutdown the drainage system including the drainpipes can be opened by manually opening valves so that the fluid in the process equipment after the well has been shut can be drained or pumped from the process equipment into the drainage tank.
The process equipment is routed around the platform so that there can be personnel access to all process equipment. This means that the personnel can operate the drainage system during shutdowns to remove the extracted fluid from the process equipment.
There is an increasing desire to minimise the amount of equipment on a wellhead platform and to reduce the amount of manual intervention which is required. This is particularly in the case of offshore unmanned wellhead platforms. This is because there will not be personnel stationed on the platform itself and so it is desirable to reduce the amount of time required to perform maintenance.